A well known and widely used type of tire press is known as a slideback press. In a slideback press the top mold sections are supported on a beam in turn supported by links from bull gears at each side of the press. As the press opens, the beam moves through slots in side plates and back along the top of such plates with a cam follower riding in a slot in such plates maintaining the top mold sections parallel to the fixed bottom mold sections throughout the opening movement. The top mold sections initially move vertically and then horizontally both to clear the bottom mold sections for concurrent loading and removal of the cured tire from the press.
Loaders for such presses have conventionally been mounted on the press beam at each end and normally include an elevator which simply moves the chucks for the uncured tires up and down. In this manner when the press is closed the chucks may descend and pick up incured tires from loader stands in front of the press and hold such tires in elevated position. Two new uncured tires may then be placed in front of the press. When the press then opens, the tires held by the loader are moved with the beam to be positioned over the bottom mold section when the press is fully opened. The loader then descends placing the uncured tires on or near the bottom mold section to be engaged by the shaping and curing bladder. When the tire is properly secured to the bladder the loader releases the tire, elevates, and the press closes. Such tire presses have been sold in large number throughout the world under the trademark AUTOFORM by NRM Corporation of Columbiana, Ohio, U.S.A. Such presses and loaders therefor are also illustrated in a number of U.S. patents, examples being: U.S. Pat. No. 3,065,499 to Brundage et al; U.S. Pat. No. 3,065,503 to Mallory et al; U.S. Pat. No. 3,097,394 to Mallory et al; and U.S. Pat. No. 4,092,090 to Yuhas et al.
Because of tolerances, wear, and controls relating to the size and type of machinery involved the full open position of the press in both an X and Y horizontal direction may vary from cycle to cycle and as the parts of the press wear. If the loader is mounted on the press head, then its final loading position may also vary slightly, resulting in less than desired accuracy in loading.
Because of the need for loading accuracy, applicant has developed a high accuracy loader for a tire press utilizing preloaded linear bearings and driven for vertical movement through a motor driven rack and pinion drive. Reference may be had to applicant's copending application filed Dec. 4, 1985, Ser. No. 804,460, now U.S. Pat. No. 4,618,320, entitled "Tire Press and Loader".
With such loader, great precision and accuracy can be achieved in pick and place or automatic transfer of large unwieldly objects such as uncured tires. However, if mounted on the beam of a tire press, the accuracy of the loader is then limited or controlled by the final positional accuracy of the beam on which it is mounted.
It is of course an advantage to mount the loader on the beam in slideback presses. It is also an advantage to utilize a high accuracy loader. The present invention enables the advantages of both to be achieved.